The disclosure relates generally to wavelength-division multiplexing (WDM) and demultiplexing, and more particularly, to WDM optical assemblies with increased lane density using a WDM filter having a passband in optical communication with two different WDM common ports.
Wavelength-division multiplexing (WDM) is a technology that multiplexes (e.g., adds) a number of distinct wavelengths of light onto a single optical fiber and demultiplexes (e.g., divides) a number of distinct wavelengths of light from a single optical fiber, thereby increasing information capacity and enabling bi-directional flow of signals. Multiple optical signals are multiplexed with different wavelengths of light combined by a multiplexer at a transmitter, directed to a single fiber for transmission of the signal, and split by a demultiplexer to designated channels at a receiver. By combining multiple channels of light into a single channel, WDM assemblies and associated devices can be used as components in an optical network, such as a passive optical network (PON).
FIG. 1A is a perspective view of a typical WDM optical core subassembly 100. In particular, the WDM optical core subassembly 100 comprises a single WDM common port 102 in optical communication with four WDM channel ports 104A-104D by a plurality of WDM filters 106A-106D, each having a width (W1), and a mirror 108 mounted to a substrate 110. The WDM optical core subassembly 100 positions all of the WDM filters 106A-106D and the mirror 108 on one surface of the substrate 110. The WDM filters 106A-106D and the mirror 108 are arranged to form an optical path 112 between the common port 102 and each of the four channel ports 104A-104D. In particular, each of the WDM filters 106A-106D has a unique passband to allow a portion of the optical signal to pass through the WDM filter 106A-106D and to reflect the remaining portion of the optical signal towards the mirror 108, which in turn reflects the remaining portion of the optical signal towards another one of the remaining WDM filters 106B-106D.
FIG. 1B is a perspective view of a WDM optical assembly 114. The WDM optical assembly 114 includes a WDM optical core subassembly 116 with a common collimator 118 and four channel collimators 120A-120D. The WDM optical core subassembly 116 includes a plurality of WDM filters 106A-106D positioned on opposing sides of a substrate 122 (WDM filter 106B is located on a bottom side of the substrate 122 and is not visible in FIG. 1B). The WDM optical core subassembly 116 further includes a trapezoidal-shaped prism 124 for routing an optical signal between upper and lower sides of the substrate 122 as the optical signal is directed between the plurality of WDM filters 106A-106D (WDM filter 106B is located on a bottom side of the substrate 122 and is not visible in FIG. 1B). However, in each of the WDM optical core assemblies 100, 114 of FIGS. 1A-1B, the WDM filters 106A-106D are in optical communication with a single WDM common port (e.g., a single common collimator 118).
One of the components in an optical network that utilizes a WDM assembly is a transceiver (e.g., pluggable transceiver), such as a quad small form-factor pluggable (QSFP) transceiver for example. In particular, a QSFP transceiver interfaces networking hardware to a network connection (e.g., fiber optic cable or electrical copper connection). The QSFP has a form factor and electrical interface specified by a multi-source agreement. Accordingly, a QSFP transceiver must meet certain dimension requirements in order to properly interface with other components.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.